Method for Providing Information on the Cooking of a Food Item, and Associated Apparatus

ABSTRACT

Provided is an apparatus for cooking a food cooked by contact, characterized in that the apparatus is made to transmit information to a user after a period of time during which the food is heated by the resistor(s) has elapsed, said period of time depending on at least one value of the internal cooking temperature of the food, which is pre-stored in a memory of the apparatus at the factory prior to the first operational use thereof.

The present invention relates to a method for implementing an apparatusfor cooking a food item, comprising at least one heating plate incontact with which the food can be cooked.

An apparatus of this type is also concerned.

The apparatuses that are known include notably the dual-surface grilleswhich comprise lower and upper heating plates between which one or morefood items that have to be cooked on contact with them are positioned.The food items can be meat, fish, vegetables or other foods.

DE 4302190 and WO 2007/149063 disclose a cooking method and apparatusthat are illustrative of the prior art.

However, these known solutions do not make it possible to provide theuser of the apparatus with suitable information, and do so in anappropriate manner.

Nor do they make it possible to provide an automatic cooking that istruly favorable to the food and to the taste of the user.

Thus, the invention aims to provide a cooking process and optimizedinformation to obtain:

-   -   a favorable organoleptic result,    -   an appropriate core cooking,    -   a texture and color to everyone's taste,    -   ease of operation for the user,    -   information enabling the user to achieve this easily,        reproducibly and relevantly,    -   a solution that is deemed practical and clear.

To tend toward the satisfaction of at least some of these objectives, amethod for implementing a cooking apparatus of the type described aboveis first proposed, which is characterized firstly in that, at the end ofa heating time of the food by one or more resistor(s), this apparatus ismade to indicate, to a user, information which is dependent on at leastone internal cooking temperature value (X) of the food stored in theapparatus.

Secondarily, which can be independent of or dependent on the above, thismethod is characterized in that:

-   -   different (so-called) internal cooking temperatures for the food        are stored in memory,    -   and to be able to deliver the food to the user with an internal        cooking as desired, the following steps are carried out:        -   said (a) placing in contact of this food with the heating            plate or plates,        -   a calculation by the apparatus of the cooking time of the            food as a function of at least one of the stored            temperatures (X),        -   and said (an) indication to the user of the (an) information            (item) indicating to him or her that the cooking has been            achieved.

Storage in memory will be able to be a prestorage stored in the factory,before the first operational use of the apparatus.

Thus, the risks of errors and the intervention of the user will belimited.

Before continuing, it will also be noted that it would be possible tochoose, when the apparatus is operating and to achieve the internalcooking of the food to a greater or lesser degree than desired by theuser, that there is selection by the user, on the apparatus, of one ofsaid stored temperatures (X), before the food is placed in contact withthe heating plate or plates.

Whatever the case, to favor the reaching of a favorable organolepticresult and of an appropriate core cooking, it is recommended that theapparatus indicate said information to the user, notably at the end ofthe calculated cooking time (T).

To the same end and for a texture and color to everyone's taste, it isrecommended that, with the apparatus operating, and when the food is incontact with the heating plate or plates, this apparatus measure thetemperature of at least one of the heating plates and:

-   -   compute the cooking time for the food also as a function of this        measured temperature,    -   and/or, when a predetermined preheating temperature is reached,        address to the user information which indicates same to him or        her.

Again to the same end, and in order to optimize the quality of theresult achieved, it is recommended that, with the apparatus operatingand when the food is in contact with the heating plate or plates, itperform:

-   -   a measurement of the thickness (Y) of the duly positioned food        and/or an estimation of the surface area (Z) occupied by this        food on the heating plate, upon which said trend of the internal        cooking temperature (X) of the food depends,    -   then said calculation of the cooking time (T) for the food as a        function of the thickness (Y) of the food, and/or of the surface        area (Z) that it occupies.

In order to simplify the intervention of the user in the operation ofthe apparatus, without affecting the quality of the cooking achieved, itis recommended that:

-   -   said calculation of the cooking time (T) for the food comprise        the calculation of a first cooking time (T), as a function of        the lowest temperature (X) out of those stored in memory,    -   at the end of said first calculated cooking time (T), there is        an indication to the user, by the apparatus, that the        corresponding cooking has been achieved, then:    -   if the user does not remove the food, there is application by        the apparatus of a second calculated cooking time (T) for the        food, as a function of the second in ascending order of said        temperatures stored in memory (X),    -   at the end of this second calculated cooking time (T), there is        once again an indication to the user, by the apparatus, that the        corresponding cooking has been achieved,    -   and so on.

Once again to simplify the intervention of the user in the operation ofthe apparatus, without affecting the quality of the cooking achieved, itis recommended that, during said operation of the apparatus, the food bepositioned between a plurality of said heating plates, in contact withthem.

Thus, there will notably be no need to turn over the food and, ifprovided, the measurement of the thickness (Y) of the food will be ableto be simplified.

To refine the quality of the cooking achieved, and therefore the benefitfor the user of the information delivered, it is recommended:

-   -   that at least one of the following steps be provided:        -   selection of the category of the food to be cooked,        -   selection of the frozen state of the food,        -   selection of a desired grille marking of the food,    -   and that the preheating temperature depends on the or said        selections made and be selected by the apparatus out of several        temperatures previously stored in memory.

Finally, again to simplify the intervention of the user in the operationof the apparatus, without affecting the quality of the cooking achieved,it is recommended that, at the end of the step (A) of preheating of theapparatus, the start of the step (B) of cooking of the food be detectedautomatically by the apparatus, by a lowering beyond a predeterminedthreshold of the measured temperature of the or of one of the heatingplates.

Now with regard to the cooking apparatus itself, which thereforecomprises at least one heating plate for cooking concerned by itscontact, it is characterized in that it comprises, to achieve aninternal cooking of the food to a greater or lesser degree desired by auser:

-   -   a memory for storing different temperatures (X) before the first        operational use of the apparatus,    -   means for measuring the thickness (Y) of the food then        positioned in contact with the heating plate or plates and/or        means for estimating the surface area (Z) occupied by this food        on the or one of the heating plates,    -   means for calculating at least one cooking time (T) for the duly        positioned food, as a function:        -   of at least one of the temperatures (X) out of those stored            in memory, and        -   of the thickness (Y) of the food, and/or of the surface            area (Z) occupied by the food; and        -   means for indication to the user, by the apparatus, of            information at the end of said calculated cooking time,            which is a function of at least one of the stored            temperature values (X).

These stored temperatures will be, or a priori comprise, temperatures(X) characteristic of internal cooking of the food, such as, forexample, for a meat: rare, medium, well done.

In order once again to simplify the intervention of the user in thecontext of the user/apparatus interface, it is recommended that theindication means comprise:

-   -   a luminous display,    -   a chromatic reference frame showing a number of colors or color        intensities, and    -   means for varying the color or the color intensity of the        display, from one color or color intensity from the reference        frame to another.

In the same context of simplicity of intervention of the user and ofrelevance of the information supplied, it is recommended that theapparatus comprise at least one temperature sensor for the heating plateor plates linked to the indication means, to have them indicate to theuser information that a predetermined preheating temperature, stored inmemory, has been reached.

To favor having the user obtain information that he or she will deempractical, relevant and clear, with a reliable solution, it is alsoproposed that:

-   -   the luminous display comprise multicolored LEDs,    -   and that the means comprise means for sequencing the colors or        color intensities by variations of chromatic coordinates.

The user could in fact wish to act him- or her-self, positively, on thischoice, via such a manual selection.

Other features and advantages of the invention will emerge clearly fromthe description given below, in the case of a common use of theabovementioned three parameters (X, Y, Z), and in an indicative and inno way limiting manner, with reference to the attached drawings, inwhich:

FIG. 1 represents an example of a cooking process according to oneembodiment of the invention;

FIG. 2 represents a lower shell of a cooking apparatus provided with twotemperature sensors, according to one embodiment of the invention;

FIG. 3 represents the two temperature curves measured by two temperaturesensors of one of the shells, such as the lower shell, and thetemperature curve measured at the core of the food as a function oftime,

FIG. 4 shows an example of cooking kinetics ensuring a cooking withmarking, independently of the number of food items on the plate, withmeasurement of temperatures by a single sensor,

FIGS. 5, 6 respectively show the trend of the temperature of thetemperature sensor provided, as a function of time and of the surfacearea occupied by the food, and the trend of the slope of the curve 2 asa function of time and of the surface area occupied,

FIGS. 7, 8 show a cooking apparatus of grille type that makes itpossible to implement the method that is the subject of the invention,

and FIG. 9 schematically represents, as indicator for the user, aluminous display with chromatic reference frame and means for varyingcolors or color intensities.

The cooking apparatus which what is described below is intended to beimplemented comprises, in the illustrations, two shells articulatedrelative to one another, including a lower shell 9 and an upper shell90; see FIG. 7. The lower shell 9 comprises a lower heating plate 61 andthe upper shell comprises an upper heating plate 63. Each shellcomprises a heating resistor 10 positioned between the heating plate andthe bottom of the shell. The food is cooked by contact between plate(s)and food items. The food may be meat, or other food.

Notably in this context, there has therefore been:

-   -   in the factory, a storage in memory 72 of the apparatus of        different internal cooking temperatures (X) for the food,    -   then, with the apparatus operating and to achieve an internal        cooking of the food to a greater or lesser degree, then desired        by the user:        -   a placing of the food in contact with the heating plate(s)            61, 63 and a calculation by the apparatus of the cooking            time for the food as a function of at least one of the            stored temperatures (X),        -   and an indication by the apparatus to the user, in the            example via the display 79, of information which depends on            the trend of said cooking temperature (X).

In other words, the information intended for the user has been indicatedby the apparatus, here via the display 79, at the end of a heating timefor the food (via the resistor(s) 10) which is a function of at leastone internal cooking temperature value (X) for the food prestored inmemory 72 of the apparatus, in the factory, before its first operationaluse.

Specifically, the apparatus has here indicated said information to theuser, notably at the end of the calculated cooking time (T).

And it has, even during cooking, measured the temperature of at leastone of the heating plates 61, 63 and calculated the cooking time for thefood also as a function of this measured temperature.

It has even also, favorably:

-   -   performed a measurement of the thickness (Y) of the duly        positioned food and/or an estimation of the surface area (Z)        occupied by this food on the heating plate, on which depends        said trend of the internal cooking temperature (X) for the food,    -   then conducted said calculation of the cooking time (T) for the        food as a function of these parameters (Y) and/or (Z).

It has been understood that the information indicated by the apparatusto the user concerns (is linked to) the cooking of the food.

To enable the user to have his or her food at the right temperature sothat it is, if necessary, seared appropriately, the apparatus has also,on reaching the predetermined preheating temperature, addressed to theuser information which has indicated it to him or her.

In this context preferably, here:

-   -   at least one of the following steps is conducted:        -   selection of the category of the food to be cooked (buttons            880 FIG. 9),        -   selection of the frozen state of the food, if such is the            case (button 881),        -   selection of a desired grille marking of the food,        -   if necessary, final validation of the choice (button 883),    -   and the preheating temperature θ′ depends on the or said        selection(s) made and is selected by the apparatus from a number        of temperatures previously stored (in 72).

To the cooking apparatus of FIGS. 7 and 8, it therefore comprises means79 for indicating to the user anticipated (cooking) information, linkedto the end having been reached of said calculated cooking time.

More specifically, FIG. 9 shows that the indication means 79, herevisual, preferably comprise:

-   -   a luminous display 83,    -   a chromatic reference frame 85 showing a number of colors or        color intensities, and    -   means 87 for varying the color or color intensity of the        display, from one color or color intensity of the reference        frame to another.

Preferably, the luminous display will comprise, as schematicallyrepresented in FIG. 9, multicolored light-emitting diodes 830 and thevariation means 87 will comprise means 870 for sequencing the colors orcolor intensities by variations of chromatic coordinates.

These means will be able to be an electronic card controlling the changeof color. The main multi-colored electronic diodes may be made up ofthree small diodes each emitting in a primary color. The controltechnique (which may be of the PWM type) may make it possible toindependently modulate the pulse widths of the three colors which makeup the diode (such as blue, green, red). All the main diodes arecontrolled independently.

The indication means 79 will favorably be linked to at least onetemperature sensor (11 or 11 a, 11 b hereinbelow) provided to detectthat of the plate or plates 61, 63, to make them indicate to the userinformation that the predetermined preheating temperature stored inmemory 72 has been reached.

As for the variation means 87, they will, at least functionally, belinked to the microcontroller(s) cited later 73, 75, 77 and therefore tothe means also cited later 65, 66, 67, 69/11 (or 11 a, 11 b), 70, 71,72, 79 and to the resistors 10, for their control.

That said, the cooking method in itself will comprise, as illustrated inFIG. 1, a preheating A) of the apparatus followed by a cooking B) of thefood for a time (T).

FIG. 1 represents, as an example, a process of cooking an unfrozen meat.The curve 1 represents the trend of the temperature measured at the coreof the food as a function of time. Here, it has been acquired in thefactory and does not necessarily exist in the marketed apparatus. Atleast some of these points are, however, entered into memory 72 of theapparatus. The curve 2 represents the trend as a function of time of thetemperature of one of the heating plates, which is measured during thecommercial operation of the apparatus. The X axis 3 represents the timein seconds, the Y axis on the left 4 represents the measured temperatureof the heating plate concerned, such as 63, and the Y axis on the right5 represents the temperature measured at the core of the food. The curve6 represents the heating cycle as a function of time (power consumed).During the step A), the measured plate temperature rises rapidly to alevel 7 corresponding to a preheating temperature. In the example 2,this temperature is approximately 230° C. Once this is reached, the foodis placed on the lower heating plate. The high contact temperature makesit possible to perform a marking on the food. A crust is then formed.

The placing of the food in the heating apparatus corresponds to thestart of the step of cooking of the food B). The measured temperature ofthe heating plate (curve 2) drops to a temperature stabilization level8, corresponding to approximately 150° C. in the example.

By way of confirmation (since a priori not available in the apparatus),the curve 1 shows that the temperature of the food rises in the meantime gradually to a temperature which is a function of the category ofthe food, even of its frozen state.

What FIG. 1 does not show is that, before any cooking process, conductedfor example with the apparatus schematically represented in FIG. 9,there has typically been able to have been, in the factory (thereforebefore the marketing of the apparatus), a storage in memory 72 of theapparatus, notably of different internal cooking temperatures (X) forthe food (preferably for several food items) making it possible toreach, for at least one given food, several core cooking levels(internal).

Then, as indicated above, it is therefore possible to choose for thereto be a positive selection by the user, on the apparatus, of one ofthese stored temperatures (X).

In this case, the apparatus having been sold, when its user goes to useit, what follows may be implemented:

-   -   powering up of the apparatus 1, for example by pressing on an        on/off button 70;    -   via the interface 67 of the apparatus, and in the menu that the        latter then displays, selection, therefore on the apparatus, by        the user, preferably first of all of a category of food to be        cooked (choice for example between meat and fish), then, here, a        degree (X) of internal cooking desired for the food, out of a        number available (if provided);    -   automatic determination:        -   of the temperatures θ: maximum preheating temperature            (before the placement of the food) taking into account the            category of the food, if the latter can be selected, and θ′:            minimum or final cooking temperature of the food (after its            placement of the food), once again taking into account its            category, if provided,        -   and of the duty cycle: changes of the electrical energy            supplied to the resistors 10 from the source provided (such            as the mains); definition and application of the variations,            which can be binary—maximum or zero—, of this energy; see            curve 6;    -   automatic preheating of the apparatus (step A), via the        resistors 10, with application of a predetermined preheating        time defined in factory tests, then entered into memory 72 and        which makes it possible to reach the stabilized temperature θ        during the interval provided;    -   with the apparatus open, placement of the food;    -   closure of the apparatus; this will preferably be necessary to        activate the start of the cooking of the food (step B), then        with, preferably automatically, a measurement of the        thickness (Y) of the food introduced between the plates 61, 63;    -   the apparatus then automatically detects an abrupt lowering of        the measured temperature of the heating plate concerned (contact        with the food), after which the temperature is substantially        stabilized; see zone 8, FIG. 1 or 3. Preferably this start of        cooking step B) will be detected:        -   as a function of this lowering of measured temperature(s)            (in time, speed, slope, etc.),        -   and, comparatively, with one or more predetermined            thresholds of the temperature drop detected;    -   from this/these temperature variation(s) measured on the plate        concerned of the grille, there may then be an estimation of the        load (or surface area occupied by the food): abovementioned        parameter (Z);    -   again preferably at the start of this cooking step, there is        also estimation/calculation by the apparatus of the required        cooking time (T). This time is therefore that, indicated for        example in FIG. 1 (T), between the moment when the food is        placed in contact with the heating plate(s) and that when it is        removed therefrom, at the end of cooking. The origin moment may        typically be that of the closure of the apparatus, if it is a        grille, followed almost immediately by the measured drop in        temperature of the plate. The end moment is also that when the        announcement that the cooking is done is made by the apparatus.        The expected temperature/degree (X) of internal cooking is        reached;    -   via, for example, a microcontroller 73, 75, and an indicator 79        accessible to the user, provision is then made for the user to        be, at the end of the calculated time, informed by the apparatus        that the expected degree (X) of cooking has been reached; the        user is thus prompted to remove his or her food;    -   the apparatus can then for example automatically keep the food        hot waiting for the user to open the apparatus;    -   the apparatus can finally be powered down, for example via the        switch 70.

Thus, the end of cooking established at the end of theestimated/calculated time T, when, once the food has been placed in thepreheated apparatus, the measured temperature, after having droppedbecause of this food, is stabilized (zone 8, FIG. 1 or 4), for examplebetween two values for which the difference has been predefined andentered into memory 72;

In addition to the above, the interface 67 with the user can be able tomake it possible to select, from the menu, the frozen state of the food(frozen or not) and/or the extent of the grille marking desired(strongly marked or other).

The interface 67 can be a touchscreen.

In the above scheme, the cooking time (T) for the food in theabovementioned step B) is determined by a process in which the followingsteps are conducted:

-   -   a step of measurement of the thickness (Y) of the food,    -   a step of estimation by the apparatus of the surface area (Z)        occupied by the food on one of the heating plates,    -   a step of calculation in the apparatus of a cooking time (T) for        the food as a function:        -   of the degree (X) of internal cooking of the food,        -   of the thickness (Y) of the food,        -   of the surface area (Z) occupied by the food.

The degrees (X) that can be selected will be able to correspond tocooking cycles that are respectively rare, medium and well done. Eachcase will have, in memory 72, a corresponding cooking temperature takenfrom the curve 1, in the factory. Thus, it will be possible to havethree parameter values, respectively 55° C., 65° C. and 75° C.

To measure the thickness (Y) of the food, sensor means 65 can beprovided on the apparatus, detecting the average distance between thelower and upper heating plates, 61, 63, and in particular their relativeseparation when the food is introduced between them. It is then possibleto obtain a food thickness which is a function of the relativedisplacement distance of the plates between them, upon the closure ofthe apparatus.

In FIG. 7, it can be seen that these heating plates are rotationallymobile relative to one another. When the upper heating plate is inhorizontal position after having been displaced toward the lower heatingplate, a positioning mechanism 66 can linearly and vertically displacethe upper heating plate (by bringing one of these plates closer to orfurther away from the other) until there is contact with the interposedfood.

By way of example, the sensor means 65 can comprise at least oneoptoelectronic inductive proximity sensor. It could alternatively be aforce sensor measuring for example the force on a spring blade via astrain gauge, or a magnetic incremental positioning sensor using theHall effect (again measuring distance).

Once the preheating is finished, the automatic triggering, by theapparatus, of the cooking step will preferably take place only if thesensor means 65 measure a value that is neither zero nor “infinity”.

In FIG. 8, it can be seen that the positioning means or mechanism 66comprise arms 660, 661 mounted articulated between the lower 9 and upper90 shells. These arms, here two of them, 660, 661, are fixed, herelaterally, close to one of the edges of each of the shells, such thattwo parallel rotation axes 9 a, 90 a (horizontal) passing through thefixings of the arms 660, 661 are defined, for the relative movementsbetween the heating plates. Opposite, a handle 81 fixed to one of theshells, here 90, assists in the maneuver.

During the step of estimation of the abovementioned surface area (Z),means for estimating this surface area determine whether the heatingplate, provided with the load sensor(s), is fully loaded, partiallyloaded, or not loaded (cooking apparatus empty). This estimation cantherefore be obtained from temperature data variations measured on (atleast) one of these plates.

The step will preferably comprise, advantageously during a predefinedtime (T) which begins from the detection of the start of the cookingstep B): —a substep of measurement of the temperature of the heatingplate fitted (upper plate 63, FIG. 7), —then a substep of determinationof this surface area (Z) as a function:

-   -   a) of time calculated to achieve a substantially zero stabilized        slope (abovementioned zone 8, FIGS. 1, 3) of the trend of this        measured temperature,    -   b) or of a drop in this temperature compared to a predetermined        threshold (value(s) in terms of amplitude, on reaching a minimum        temperature and/or in terms of slope(s) with, in the case a),        the existence of a relationship between the surface area and the        quantity of energy to be provided to compensate the heat losses        due to the placement of the food.

The calculation of this parameter will be able to be done by acomputation means such as a microcontroller with which the apparatus isequipped.

With a multi-sensor solution, such as, for example, with the twotemperature sensors 11 a, 11 b, shown in FIG. 2 (even if it might bepreferred to place a first sensor centered on one side (such as 11 a inFIG. 3), and a second off-center), comparisons, preferably of slopevalues, calculated for one and the other of these sensors, with apredetermined threshold, stored in memory 72, will be able to make itpossible to define the parameter values (Z) to be used.

With the solution with two temperature sensors 11 a, 11 b shown in FIG.2, and if the parameter retained is the slope, the following thresholdswill be able to be considered:

-   -   if slope>−0.5° C./s for the two sensors=>surface area Z has        little or no load=>value Z1,    -   if slope<−0.5° C./s for one of the sensors, with=>surface area Z        averagely loaded=>value Z2,    -   if slope<−0.5° C./s for the two sensors=>surface area Z fully        loaded=>value Z3.

For the temperature sensor(s), it will be possible to choose probes withnegative temperature coefficient (NTC). They will be able to be housedbehind the heating plate which covers them internally.

Computation means then make it possible to calculate the cooking time(T) for the food as a function of the degree of the internal cookingtemperature (X) desired, here selected, for the food, of the thickness(Y) of the food, and/or of the surface area (Z) that it occupies.

This cooking time (T) for the food can be determined by a quadraticcorrelation calculation method with the following second degreefunction:

T(X,Y,Z)=A1+A2*X+A3*Y+A4*Z+A5*X ² +A6*Y ² +A7*Z ²+A8*X*Y+A9*X*Z+A10*Y*Z.  (1)

The coefficients A1, A2, A3, A4, A5, A6, A7, A8, A9 and A10 arepredefined for each menu, for predefined temperature conditions. Theyare stored in storage means (such as the memory 72). They are constants.

As a variant, the cooking time (T) for the food can be determined by alinear correlation calculation method with the following first degreefunction:

T(X,Y,Z)=B1+B2*X+B3*Y+B4*Z  (2)

The coefficients B1, B2, B3 and B4 are predefined for each menu, forpredefined temperature conditions. They are stored in said storage means(memory 72 for example). They are constants.

Regarding the estimation of the surface area occupied by the food items,the possibility of an estimation of the surface area (Z) via (at least)two temperature sensors (values Z1, Z2, etc.) has been described above.

Another possibility consists in using only a single energy sensor (item11, FIG. 7) which can be a temperature probe placed, as previously, incontact with one of the heating plates. Favorably, this sensor will beremotely cited at (toward) the periphery of the heating plate concerned,facing a zone of the plate where food should not (or cannot) be placed.The sensor will be able to fulfill two functions, in conjunction withthe microcontroller(s):

-   -   regulating the temperature of the plate,    -   measuring the quantity of energy to be provided to compensate        the losses linked to the presence of the food or foods on the        plate. Assuming that the food items are steaks (see FIGS. 4-6),        it will be possible to correlate this with the number of such        steaks present being cooked on the plate, or the extent of the        occupied surface area.

Thus:

-   -   a slope beyond a first threshold retained and stored in memory        72 will be able to correspond to a heating plate fully occupied        by the food,    -   a slope below a second threshold will be able to correspond to        an unoccupied heating plate,    -   and a slope between the two thresholds will be able to        correspond to a partially occupied heating plate.

To illustrate this, FIG. 4 shows an example of cooking kineticsestablished on the following basis: cooking of three joints/steaks cutfrom a topside round, common thickness of 29 mm, identical surface areasof the plates 61, 63 substantially fully occupied (except just at theperiphery where the temperature sensor 11 is located; FIG. 7), expectedcore temperature (at the end of cooking) of approximately 60° C.,cooking time of approximately 23 min (calculated).

These kinetics could be considered to be valid regardless of the surfacearea estimation method used; it could therefore replace the illustrationof FIG. 1 where the curve 2 concerned a multi-sensor application.

In FIG. 4, the X axis represents the time in seconds, the Y axis on theleft 4 represents the temperature (° C.). The Y axis on the right 50represents the thickness (mm) of the food. The curve 21 represents thetrend of the thickness of the food/food items present on the heatingplate as a function of time. The trend of the curve 2 is comparable tothat of FIG. 1 (see comments above). After the step A (=A1+A2) ofpreheating, the placing of the food in the heating apparatus correspondsto the start of the step B (=B1+B2) of cooking of this food.

There occur:

-   -   a cooking in two phases:        -   a phase B1 of marking;        -   a phase B2 of cooking at lower temperature, to allow time            for the heat to migrate to the core without risking charring            the periphery;    -   a marking time approximately proportional to the exchange        surface area (Z) and therefore to the quantity of food.

Throughout the phase 22 marked by a broken outline square in which thereis marking of the food (or food items), there is no reversal of thecycle of delivery of the electrical power (the electrical power/energydelivered to the resistors remains maximum).

This is preferably the interval during which the analysis phase (B1,broken outline square 22, FIG. 4) is performed: values Y and/or Z,calculated time T.

Regarding the estimation of the surface area (Z) occupied by the fooditems, FIGS. 5, 6 show respectively:

-   -   the trend of the detected temperature as a function of time and        of said occupied surface area,    -   the trend of the slope of the curve 2 as a function of time and        of the occupied surface area.

In FIGS. 5, 6, the origin of the time (T=0) is the moment of placementof the food in the heating apparatus, i.e. here (as indicated in FIGS. 1and 4) the start of the step of cooking of the food (B).

In FIG. 5, the curves 23, 24, 25 correspond respectively to the steakcases 1, 2, 3. The circles 26, 27, 28 show the respective slopecancellations.

In FIG. 6, the Y axis corresponds to the slope (in ° C./s), the X axisis the time (in s).

The curves 29, 30, 31 correspond respectively to the steak cases 1, 2,3. The circles 33, 35, 37 show the respective slope cancellations(passage through the time X axis).

The analysis of the slope concerned makes it possible to reveal thatthere are correlations between:

-   -   the exchange surface area and the minimum slope, or the        temperature drop at a given instant,    -   the exchange surface area and the instant when the slope is        cancelled (instant when the slopes linked to the exchanges        between the food items and the plate have been compensated).

The second relationship (FIG. 6) is deemed more reliable because it isless dependent on the accuracy of the calculations (see dispersion oncurve with the steak) and on the position of the sensor on the plate.

Two methods can be envisaged for estimating the occupied surface area:

-   -   establishing, via experimentation conducted in the factory,        before the marketing of the apparatus, the affine function        (y=ax+b) which links the occupied surface area to the instant        when the slope reversed,    -   identifying three zones:        -   zone A, plate with little load (1/3 of the plate occupied),        -   zone B, plate with average load (2/3 plate),        -   zone C, plate strongly loaded (3/3 plate),    -   then testing the correspondence of the system to one or other of        these three zones.

This method is potentially easier to synchronize with the communicationto the user of the corresponding information (indicator 79).

In this case:

-   -   it is essential for the sensor 11 to be positioned on a zone        without food, such as the perimeter of the plate:    -   the following are taken into account, as explained above:        -   the existence of a correlation between the reversal of the            slope of trend of the temperature detected by the sensor and            the exchange surface area between the heating plate            concerned and the food (the food items) positioned against            this plate: passage through a zero trend slope; see above,        -   the existence of a correlation between the minimum slope and            said exchange surface area.

From the above, it will have been understood that two methods havetherefore been considered for estimating the occupied surface area:

-   -   the first that can use only a single temperature sensor 11        remotely cited at the periphery of the plate concerned,        therefore with the existence of a relationship between the        surface area occupied by the interposed food and the quantity of        energy to be provided to compensate for losses (time observed        for a slope of the curve 2 equal to zero), or a greater or        lesser temperature drop (temperature threshold), or a faster or        slower temperature drop (slope threshold),    -   a second using a number of temperature sensors, such as 11 a, 11        b, distributed on or under the plate concerned, then with the        presence or not of food (food items) in the vicinity of two,        three, or even four sensors.

It should also be noted that, if the temperature sensor(s) 11 or 11 a,11 b are positioned in such a way that it (they) detects (detect) thetemperature of the cooking plate (here upper) which comes into contactwith the food only when the two plates 61, 63 are displaced relative toone another to close the apparatus (moment when the cooking time=0), itwill then be possible to have two information items for triggering thestart of the cooking (phase B): that obtained from the temperaturesensor(s) and that from the thickness sensor.

In FIG. 7, it will also be noted that the cooking apparatus 60 of meatgrille type therefore comprises the lower 61 and upper 63 heatingplates, as follows:

-   -   the means 65 for measuring the thickness (Y) of one or more food        items (here called “food” 80), such as the abovementioned steak        or steaks (these means 65 are linked functionally to the means        66 for relative convergence/separation of the plates 61, 63),    -   the selection means 67 for selecting, from several prestored        options, the degree/temperature (X) of internal cooking desired        for the food;    -   means 69 for estimating the surface area (Z) occupied by the        food on one of the heating plates; and    -   means 71 for calculating the cooking time (T) for the food.

A cooking chamber 600 for the food (FIG. 7) is defined between the lower61 and upper 63 heating plates.

The means 69 for estimating the surface area (Z) comprise theabovementioned temperature sensor 11 or sensors 11 a, 11 b.

To best carry out the estimation of the surface area (Z) occupied by thefood 80, it is also recommended that the means 71 for calculating thecooking time (T) for the food comprise the microcontroller 73 configuredto determine the slope of the temperature curve obtained from theabovementioned temperature measurements.

And, to the same end, it is also recommended that, with thesetemperature measurements, this microcontroller, or another 75:

-   -   regulate the temperature of the heating plate 61 or 63, and    -   change the quantity of energy to be supplied, by the resistor or        resistors 10, as a function of the extent of the surface area        occupied by said food items on the heating plate concerned, in        order therefore to compensate the temperature drops linked to        the placement of these food items between the plates.

The microcontrollers 73, 75 can be combined in a central microcontroller77. The microcontroller(s) is/are linked to the abovementioned means 65,66, 67, 69/11 (or 11 a, 11 b), 70, 71, 72, 79 and to the resistors 10,for their control.

Regarding the taking into account of the degree (X) of internal cookingto be achieved for the food, it has already been understood that it ispossible to dispense with the step described above of selection by theuser of one of said temperatures stored in memory for this purpose (itis recalled that the abovementioned steps of storage in memory 72, inthe factory, of data, algorithms, etc., as mentioned above, are alwaysperformed identically).

In this case, when the user decides to use the apparatus that he or shehas just bought, he or she simply has to engage the latter which is setto preheating mode, as already explained.

The following then take place:

-   -   when the apparatus is functioning and to achieve a greater or        lesser internal cooking of the food then desired by a user, the        user places the food in contact with the heating plate or        plates, such as 61, 63,    -   the apparatus then calculates a first cooking time (T) for the        duly positioned food, as a function of the lowest        temperature (X) out of those stored in memory,    -   at the end of this first calculated cooking time (T), the        apparatus indicates to the user that the corresponding cooking        has been achieved (via, for example, the indicator 79), then:    -   if the user does not remove the food, the apparatus        automatically applies a second calculated cooking time (T) for        the food, as a function of the second in ascending order of said        temperatures stored in memory (X); it will be well understood        from the above that this second calculated cooking time makes it        possible to increase the cooking of the food which will thus be        cooked more,    -   at the end of this second calculated cooking time (T), the        apparatus once again indicates to the user that the        corresponding cooking has been achieved,    -   and so on.

As already explained, the apparatus will, during operation:

-   -   measure the thickness (Y) of the food then positioned against        said heating plate and/or estimate the surface area (Z) occupied        by this food on this heating plate,    -   calculate the cooking time (T) for the duly positioned food, as        a function:        -   in addition to said internal cooking temperature (X) out of            those stored in memory,        -   of the thickness (Y) of the food and/or of the surface            area (Z) occupied by the food.

For the remainder, the explanations have already been given; they remainvalid.

It should however be noted that it is here considered that a cookingapparatus that is heated electrically, by resistors, would address theissue already described, provided that it comprised:

-   -   in addition to at least one heating plate on which to position        the food to be cooked, and in conjunction with a microcontroller        (such as 73, 75, 77) provided in the apparatus,    -   means for estimating a surface area (Z) occupied by the food on        the heating plate, via at least one temperature sensor (such as        11, 11 a, 11 a) which:        -   regulates the temperature of the heating plate for which it            measures the temperature, and        -   changes the quantity of electrical energy to be supplied, as            a function of the extent of the surface area occupied by the            food on the heating plate, in order to compensate the            temperature drops linked to the placement of the food, or of            the food items, on one of the heating plates, or between            these heating plates.

The means for estimating a surface area (Z) will be able to be those ofthe description on the preceding pages.

Regarding the apparatus concerned that is the subject of the presenttopic, it could also be an apparatus comprising only a single heatingplate for cooking food by contact.

A cooking pan or any cooking utensil with a lid receiving, on contactwith it, a food to be cooked (saucepan, cooking pot, etc.) ought to besuitable, provided that it would be linked to a controllable heat sourceas will have been understood from the above.

Notably in this case, provision could be made for the means formeasuring the thickness (Y) of the food placed in contact with theheating plate to be a cover positioned movably on the utensil andprovided with the suitable sensor already described. The cover could beannular.

To favor the contact between food and heating plate(s), each plate will,in any case, be preferably full. A grille solution would not then besuitable.

In the above, with reference to the solutions illustrated, provision hasbeen made for the or each (useful) internal cooking temperature value(X) for the food to be prestored in memory of the apparatus, in thefactory, before the first operational use of this apparatus. Provisioncould however be made for this (these) datum (data) to be entered intomemory 72 by the user, for example via the interface 67. Thus, provisioncan be made for the user to enter into memory 72 a cooking temperaturevalue (X) of 45° C., for a meat that is desired to be rare. In thiscase, there could be no storage in memory in the factory (thereforebefore the marketing of the apparatus) of the or any different internalcooking temperatures (X) for the food.

It will also be noted that, when used alone, independently of thecombination of the other abovementioned features, the following methodwould also address the issues described above: method for implementing acooking apparatus that is electrically heated and comprising at leastone heating plate on which to position a food item (for cooking bycontact), said method comprising a step of preheating A) of theapparatus followed by a step of cooking of the food B), the start of thecooking step B) being marked, and possibly detected, by a loweringbeyond a predetermined threshold of the temperature of the heatingplate.

1. A method for implementing an apparatus for cooking a food item,comprising at least one heating plate for cooking the food by contact,characterized in that, at the end of heating of the food by one or moreresistor(s), the apparatus is made to indicate, to a user, informationwhich depends on at least one internal cooking temperature value (X) ofthe food stored in the apparatus.
 2. The method as claimed in claim 1,wherein: different said internal cooking temperatures of the food arestored in memory of the apparatus, and, to be able to deliver the foodto the user with an internal cooking as desired, the following steps arecarried out: said placing in contact of this food with the heating plateor plates, a calculation by the apparatus of the cooking time of thefood as a function of at least one of the stored temperatures (X), andsaid indication to the user of the information indicating to him or herthat the cooking has been achieved.
 3. The method as claimed in claim 1,wherein the or each internal cooking temperature value (X) of the foodstored in memory of the apparatus is prestored in the factory, beforethe first operational use of the apparatus.
 4. The method as claimed inclaim 1, wherein the apparatus indicates said information to the usernotably at the end of the calculated cooking time (T).
 5. The method asclaimed in claim 1, wherein, with the apparatus operating and when thefood is in contact with the heating plate or plates, it measures thetemperature of at least one of the heating plates and calculates thecooking time of the food also as a function of this measuredtemperature.
 6. The method as claimed in claim 1, wherein, with theapparatus operating and before the food is in contact with the heatingplate or plates, it measures the temperature of at least one of theheating plates and, when a predetermined preheating temperature isreached, addresses to the user the information indicating same to him orher.
 7. The method as claimed in claim 1, wherein, with the apparatusoperating and when the food is in contact with the heating plate orplates, it performs: a measurement of the thickness (Y) of the dulypositioned food and/or an estimation of the surface area (Z) occupied bythis food on the heating plate, upon which said trend of the internalcooking temperature (X) of the food depends, then said calculation ofthe cooking time (T) for the food as a function of the thickness (Y) ofthe food, and/or of the surface area (Z) that it occupies.
 8. The methodas claimed in claim 1, wherein: the cooking time (T) for the food iscalculated by calculating a first cooking time (T), as a function of thelowest temperature (X) out of those stored in memory, at the end of saidfirst calculated cooking time (T), indication to the user, by theapparatus, that the corresponding cooking has been achieved, then: ifthe user does not remove the food, the application by the apparatus of asecond calculated cooking time (T) for the food, as a function of thesecond in ascending order of said temperatures stored in memory (X), atthe end of this second calculated cooking time (T), once again anindication to the user, by the apparatus, that the corresponding cookinghas been achieved, and so on.
 9. The method as claimed in claim 1,wherein, during said operation of the apparatus, the food is positionedbetween a plurality of said heating plates, in contact with them. 10.The cooking method as claimed in claim 6, wherein: it comprises at leastone of the following steps: selection of the category of the food to becooked, selection of the frozen state of the food, selection of adesired grill marking of the food, and the preheating temperaturedepends on the or said selections made and is selected by the apparatusout of several temperatures previously stored in memory.
 11. The cookingmethod as claimed in claim 5, wherein, at the end of the step (A) ofpreheating of the apparatus, the start of the step (B) of cooking of thefood is detected by a lowering beyond a predetermined threshold of themeasured temperature of the or of one of the heating plates.
 12. Acooking apparatus for implementing the method as claimed in claim 1, theapparatus comprising at least one heating plate for cooking a food bycontact, characterized in that it comprises, to be able to deliver to auser the food with an internal cooking as desired: a memory for storingdifferent internal cooking temperatures (X) of the food, means formeasuring the thickness (Y) of the food then positioned in contact withthe heating plate or plates and/or means for estimating the surface area(Z) occupied by this food on the or one of the heating plates, means forcalculating at least one cooking time (T) for the duly positioned food,as a function: of at least one of the internal cooking temperatures (X)out of those stored in memory, and of the thickness (Y) of the food,and/or of the surface area (Z) occupied by the food; and means forindication to the user, by the apparatus, of information at the end ofsaid calculated cooking time, which is a function of at least one of thestored cooking temperature values (X).
 13. The apparatus as claimed inclaim 12, herein the indication means comprise: a luminous display, achromatic reference frame showing a number of colors or colorintensities, and means for varying the color or the color intensity ofthe display, from one color or color intensity from the reference frameto another.
 14. The apparatus as claimed in claim 12, wherein itcomprises at least one temperature sensor for the heating plate orplates linked to the indication means, to have them indicate to the userinformation that a predetermined preheating temperature stored in memoryhas been reached.
 15. The apparatus as claimed in claim 13, wherein theluminous display comprises multicolored light-emitting diodes, and themeans comprise means for sequencing the colors or color intensities byvariations of chromatic coordinates.